1. Field of the Invention
This invention is in the field of manufacturing hydraulic binders and involves selective withdrawal of partly processed material from a cement producing installation and further processing of the withdrawn material to make it suitable for use in a hydraulic binder composition.
2. Description of the Prior Art
The usual method for producing a hydraulic binder for use in plaster or masonry mortar utilizes a base of limestone or clay, and activates these materials thermally at temperatures between 450.degree. and 900.degree. C. By "activation" is meant the liberation of water of crystallization, for example, with plaster of Paris, the liberation of binding water contained in hydroxyl groups in the case of mineral clays, and the liberation of carbon dioxide, called deacidification, in the treatment of calcium carbonate.
For the production of these products, simple shaft furnaces or blast furnaces are suitable and, in some cases, relatively small rotary kilns can be used. Hydraulic binders have sometimes been produced in installations producing cement clinker by means of low combustion, if such an installation permitted the use of this type of method. Largely, such installations utilized pellets or granules as the starting materials.
In the case of other installations, for example, in the manufacture of cement clinker by the dry method which normally uses a suspension gas heat exchange system for preheating and calcination, and calcination of the mixture of the raw material as a meal, the production of such products is not feasible for technical and economical reasons. Largely this is due to the reluctance to set up a separate production installation with additional costs for the production of the hydraulic binder.